I met up with Bermondsey street bees late this summer, who run their business from around central london
They put and maintain many hives on different high rise locations for corporate and private clients. The biggest problem they have is the lack of forage for colonies right in the urban areas.. Too many hives in one location and sometimes possible too high.
Ive always been told to have a maximum of 15 hives per apiary, here in Brittany, but other areas i know can support colonies better. Other parts of the world, 30 is easily possible.
I know of beekeepers in central Paris, who despite having access to many roof to gardens, still struggle for forage. The honey is unique, but one could question at what price? Are their bees really as good (in health terms) as those who have access to more biodiverse areas. I am not convinced its all as good as its cracked up to be. ( the forage and bee health not the beekeepers!)
Then there is the issue that bees in urban areas have less pesticide, but are they flying in more polluted skies!
My point is, to have healthy hives, you need good diverse forage. if your a roof top beekeeper your hives must have this, or not many hives.
Whats the point of having 10 hives with half a super full, where half the number of hives would give you the same crop, with an awful lot less work and better stronger colonies as well as a lot less humping stuff up and down stairs from Hell!!
Theres no doubt, hives on roof tops are seen as being green and eco friendly, saving the bees and the planet and an iconic thing to have! prices of the honey are enormous.
http://www.beekeepingforum.co.uk/attachment.php?attachmentid=13830&stc=1&d=1482275140